Friday, May 29, 2009

Citrix Session Slowness

Recently i faced a very strange issues regarding Citrix sessions. Users are complaining that they are getting very slow response whenever they open Citrix website from web interface. After initial analysis it has been noted that there is almost 3 minutes delay in displaying web interface page after successful authentication. After further analysis and also getting help from Citrix support it has been found that there is no reverse DNS zone entry in DNS servers for Citrix severs subnet. Because the environment is new and the application which is facing problem is the first application, so the issue has not been identified before. After entering Citrix Servers Subnet in reverse lookup zone the performance is dramatically increased and the web interface page is now opening in seconds.

As per Citrix support “You have a DNS resolution issue on the WI server just when the client machine send the login information to WI, the WI box does a DNS query to 10.201.X.X which fails for X.X.201.10.in-addr.arpa. after several DNS queries exchanges with different DNS servers, a NetBios call succeed to return 10.201.X.X and then the Citrix XML communication starts.” (They have also told us to disable SNMP which was not enabled because we are not using it)

Following tests has been conducted in order to narrow down this issues;

1. Network trace on the workstation.

2. Network trace on the XML broker server.

3. Network trace on the web interface server.

4. CDF trace on below modules on XML broker server:

IMA_Subsystems_ComSrv

IMA_Subsystems_MfServer

IMA_Sals_MfServer

MF_XMLRelay_Admin

MF_XMLRelay_Wpnbr

5. CDF trace on below modules on Zone Data collector server :

IMA_Subsystems_UserWin

IMA_Subsystems_ComApp

IMA_Subsystems_ComSrv

IMA_Subsystems_MfServer

MF_DLL_Ccticket

IMA_Subsystems_MfApp

IMA_Subsystems_User

IMA_Sals_MfServer

IMA_Sals_User

IMA_Sals_UserWin

IMA_RunTime_DynamicStore

For CDF tracing CDF Control Application is required which can be downloaded from following link;